Hydrocarbyl dispersants and compositions containing the dispersants

ABSTRACT

A dispersant for use as a lubricant additive, a lubricant composition and a method for improving engine performance. The dispersant includes at least one member selected from the group consisting of hydrocarbyl-substituted succinimides, hydrocarbyl-substituted amines, and Mannich base adducts derived from hydrocarbyl-substituted phenols condensed with aldehydes and amines. The hydrocarbyl substituent is composed of a polymerization product of a raffinate I stream and isobutylene having a number average molecular weight ranging from about 500 to about 3000 as determined by gel permeation chromatography and more than about 70 mol percent of the polymerization product having a terminal vinylidene group.

TECHNICAL FIELD

The following disclosure is directed to dispersants for lubricantapplications, crankcase dispersants, crankcase lubricant compositionsand methods for improving engine performance using novel wear reducinglubricant compositions.

BACKGROUND

Dispersants are important additives for lubricant compositions.Dispersants maintain impurities and deposits in a suspended state sothat they can be removed from the system by filtration or other meansrather than being deposited on internal engine components.

Of the dispersants commonly used in lubricant applications, polymericMannich base additives, hydrocarbyl amine adducts, and hydrocarbylsuccinic acid derivatives provide exhibit excellent properties for suchapplications. Mannich base dispersants are typically produced byreacting alkyl-substituted phenols with aldehydes and amines, such as isdescribed in U.S. Pat. Nos. 3,539,633; 3,697,574; 3,704,308; 3,736,535;3,736,357; 4,334,085; and 5,433,875.

Hydrocarbyl succinic acid based dispersants are derived by alkylating,for example, maleic anhydride, acid, ester or halide with an olefinichydrocarbon to form an acylating agent as described in U.S. Pat. No.5,071,919 to DeGonia et al. The acylating agent is then reacted with anamine to form a dispersant. A preferred olefinic hydrocarbon ispolyisobutene, also referred to as polyisobutylene.

Despite the wide variety of dispersants available for lubricantapplications, there remains a need for improved dispersants,particularly for crankcase lubricant applications.

SUMMARY OF THE EMBODIMENTS

In one embodiment herein is presented a dispersant for use as alubricant additive, a lubricant composition and a method for improvingengine performance. The dispersant includes at least one member selectedfrom the group consisting of hydrocarbyl-substituted succinimides,hydrocarbyl-substituted amines, and Mannich base adducts derived fromhydrocarbyl-substituted phenols condensed with aldehydes and amines. Thehydrocarbyl substituent is composed of a polymerization product of araffinate I stream and isobutylene having a number average molecularweight ranging from about 500 to about 3000 as determined by gelpermeation chromatography and more than about 70 mol percent of thepolymerization product having a terminal vinylidene group.

In another embodiment there is provided a lubricant additive composed ofa first dispersant including at least one member selected from the groupconsisting of hydrocarbyl-substituted succinimides,hydrocarbyl-substituted amines, and Mannich base adducts derived fromhydrocarbyl-substituted phenols condensed with aldehydes and amines; anda second dispersant including a member selected from the grouphydrocarbyl-substituted succinimides, hydrocarbyl-substituted amines,and Mannich base adducts derived from hydrocarbyl-substituted phenolscondensed with aldehydes and amines. The hydrocarbyl substituent of thefirst dispersant has a number average molecular weight ranging fromabout 1500 to about 2500 as determined by gel permeation chromatography.The second dispersant has a number average molecular weight ranging fromabout 500 to about 1200 as determined by gel permeation chromatography.

In yet another embodiment, a method of reducing engine deposits in aninternal combustion engine of a vehicle is provided. The method includesusing as a crankcase lubricating oil for the internal combustion enginea lubricant composition containing a lubricant and a lubricant additive.The lubricant additive includes a first dispersant including at leastone member selected from the group consisting of hydrocarbyl-substitutedsuccinimides, hydrocarbyl-substituted amines, and Mannich base adductsderived from hydrocarbyl-substituted phenols condensed with aldehydesand amines; and a second dispersant including a member selected from thegroup hydrocarbyl-substituted succinimides, hydrocarbyl-substitutedamines, and Mannich base adducts derived from hydrocarbyl-substitutedphenols condensed with aldehydes and amines. The hydrocarbyl substituentof the first dispersant has a number average molecular weight rangingfrom about 1500 to about 2500 as determined by gel permeationchromatography. The second dispersant has a number average molecularweight ranging from about 500 to about 1200 as determined by gelpermeation chromatography. The lubricant additive is present in thelubricant composition in an amount sufficient to reduce engine depositsand provide at least a pass rating on an engine deposit test.

An advantage of the embodiments described herein is that it providesimproved dispersants for lubricant compositions, lubricant compositionscontaining the improved dispersants, and methods for improving engineperformance using the improved dispersants. Dispersants in thelubricating oil suspend thermal decomposition and oxidation products,such as soot and sludge, and reduce or retard the formation of depositson lubricated surfaces. Dispersants for wear reducing additives areprovided by an additive having a hydrocarbyl substituent provided by apolymerization product of a raffinate I stream and isobutene. Suchdispersants are effective to meet or exceed GF-4 specifications forpassenger car motor oils.

The dispersant described herein is particularly suitable for crankcaselubricants for diesel and gasoline engines, as a dispersant forautomatic transmission fluids, as an additive for continuously variablegear oils, and as a component of hydraulic oils. Other features andadvantages of the of the dispersant will be evident by reference to thefollowing detailed description which is intended to exemplify aspects ofthe preferred embodiments without intending to limit the embodimentsdescribed herein.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As used herein, the term “hydrocarbyl substituent” or “hydrocarbylgroup” is used in its ordinary sense, which is well-known to thoseskilled in the art. Specifically, it refers to a group having a carbonatom directly attached to the remainder of the molecule and having apredominantly hydrocarbon character. Examples of hydrocarbyl groupsinclude:

-   -   (1) hydrocarbon substituents, that is, aliphatic (e.g., alkyl or        alkenyl), alicyclic (e.g., cycloalkyl, cycloalkenyl)        substituents, and aromatic-, aliphatic-, and        alicyclic-substituted aromatic substituents, as well as cyclic        substituents wherein the ring is completed through another        portion of the molecule (e.g., two substituents together form an        alicyclic radical);    -   (2) substituted hydrocarbon substituents, that is, substituents        containing non-hydrocarbon groups which, in the context of the        description herein, do not alter the predominantly hydrocarbon        substituent (e.g., halo (especially chloro and fluoro), hydroxy,        alkoxy, mercapto, alkylmercapto, nitro, nitroso, and sulfoxy);    -   (3) hetero-substituents, that is, substituents which, while        having a predominantly hydrocarbon character, in the context of        this description, contain other than carbon in a ring or chain        otherwise composed of carbon atoms. Hetero-atoms include sulfur,        oxygen, nitrogen, and encompass substituents such as pyridyl,        furyl, thienyl and imidazolyl. In general, no more than two,        preferably no more than one, non-hydrocarbon substituent will be        present for every ten carbon atoms in the hydrocarbyl group;        typically, there will be no non-hydrocarbon substituents in the        hydrocarbyl group.

Of the hydrocarbyl substituents, olefinic hydrocarbons are particularlypreferred for the hydrocarbyl substituent of at least one dispersant.Olefinic hydrocarbons such as isobutene are typically made by cracking ahydrocarbon stream to produce a hydrocarbon mixture of essentiallyC₄-hydrocarbons. For example, thermocracking processes (streamcracker)produce C₄ cuts comprising C₄ paraffins and C₄ olefins, with a majorcomponent being isobutene. Butadiene and acetylene are substantiallyremoved from the stream by additional selective hydrogenation orextractive distillation techniques. The resulting stream is referred toas “raffinate I” and is suitable for polyisobutylene (PIB) synthesis andhas essentially the following typical composition: 44-49% of isobutene,24-28% of 1-butene, 19-21% of 2-butene, 6-8% of n-butane, 2-3% ofisobutane. The components of the raffinate I stream may vary dependingon operating conditions. Purification of the raffinate I stream providesan essentially pure isobutene product.

Until now, relatively low molecular weight PIB for use in makingdispersants for lubricant and oil compositions has been derived mainlyfrom polymerization of isobutene. The resulting product typically has avinylidene group content ranging from about 50 to about 60 percent byweight of the polymerization product. The vinylidene group content isbelieved to have an effect on the reactivity of the PIB during analkylation process for making a succinic acid adduct, an amine adduct,or an alkyl phenol adduct.

A hydrocarbyl substituent made from the polymerization of a mixture ofraffinate I and isobutene has advantages over polyisobutylene (PIB)derived from isobutene alone. For example, such a hydrocarbylsubstituent is relatively more reactive than PIB as evidenced by itsvinylidene group content. The vinylidene content of a polymerizedmixture of raffinate I and isobutene is typically above about 70% byweight. Also, the polymerized mixture, as described herein, provides ahydrocarbyl polymeric chain including a mixture of gem-dimethyl carbonatoms, methylene carbon atoms, mono-methyl substituted carbon atoms,mono-ethyl substituted carbon atoms. In contrast, polymerization of arelatively pure isobutene reactant provides a mixture of gem-dimethylcarbon atoms and methylene carbon atoms only.

A preferred polymerization product is provided by polymerizing a mixtureof from about 35 to about 45 percent by weight isobutene with from about55 to about 65 percent by weight raffinate I stream containing at leastabout 40% by weight isobutene. The resulting polymerization product hasa vinylidene group content of above about 70 percent by weight andpreferably, a number average molecular weight ranging from about 500 toabout 3000, preferably from about 500 to about 2500 as determined by gelpermeation chromatography. Relatively high molecular weightpolymerization products have a number average molecular weight rangingfrom about 1500 to about 2500. Relatively low molecular weightpolymerization products have a number average molecular weight rangingfrom about 500 to about 1200. Both high and low molecular weightpolymerization products may be used to make dispersants suitable forlubricant applications.

The polymerization reaction used to form the polymerization product isgenerally carried out in the presence of a conventional Ziegler-Natta ormetallocene catalyst system. The polymerization medium can includesolution, slurry, or gas phase processes, as known to those skilled inthe art. When solution polymerization is employed, the solvent may beany suitable inert hydrocarbon solvent that is liquid under reactionconditions for polymerization of alpha-olefins; examples of satisfactoryhydrocarbon solvents include straight chain paraffins having from 5 to 8carbon atoms, with hexane being preferred. Aromatic hydrocarbons,preferably aromatic hydrocarbons having a single benzene nucleus, suchas benzene and toluene; and saturated cyclic hydrocarbons having boilingpoint ranges approximating those of the straight chain paraffinichydrocarbons and aromatic hydrocarbons described above, are particularlysuitable. The solvent selected may be a mixture of one or more of theforegoing hydrocarbons. When slurry polymerization is employed, theliquid phase for polymerization is preferably liquid propylene. It isdesirable that the polymerization medium be free of substances that willinterfere with the catalyst components.

Improved dispersant compositions may include dispersants made with thepolymerization product described above as the hydrocarbyl group. Otherdispersant compositions include at least first and second dispersantseach selected from the group consisting of, but not limited to, ashlessdispersants such as hydrocarbyl-substituted succinimides,hydrocarbyl-substituted amines, and Mannich base adducts derived fromhydrocarbyl-substituted phenols condensed with aldehydes. The firstdispersant preferably has a hydrocarbyl-substituent having a numberaverage molecular weight ranging from about 1500 to about 2500 asdetermined by gel permeation chromatography, and the second dispersantpreferably has a hydrocarbyl-substituent having a number averagemolecular weight ranging from about 500 to about 1200 as determined bygel permeation chromatography. In a particularly preferred embodiment,the first dispersant is a post treated dispersant and the seconddispersant includes a hydrocarbyl-substituent polymerized from a mixtureof raffinate I and isobutene as described above.

Hydrocarbyl-substituted succinic acylating agents are used to makehydrocarbyl-substituted succinimides. The hydrocarbyl-substitutedsuccinic acylating agents include, but are not limited to,hydrocarbyl-substituted succinic acids, hydrocarbyl-substituted succinicanhydrides, the hydrocarbyl-substituted succinic acid halides(especially the acid fluorides and acid chlorides), and the esters ofthe hydrocarbyl-substituted succinic acids and lower alcohols (e.g.,those containing up to 7 carbon atoms), that is, hydrocarbyl-substitutedcompounds which can function as carboxylic acylating agents. Of thesecompounds, the hydrocarbyl-substituted succinic acids and thehydrocarbyl-substituted succinic anhydrides and mixtures of such acidsand anhydrides are generally preferred, the hydrocarbyl-substitutedsuccinic anhydrides being particularly preferred.

Hydrocarbyl substituted acylating agents are made by reacting apolyolefin of appropriate molecular weight (with or without chlorine)with maleic anhydride. Similar carboxylic reactants can be used to makethe acylating agents. Such reactants include, but are not limited to,maleic acid, fumaric acid, malic acid, tartaric acid, itaconic acid,itaconic anhydride, citraconic acid, citraconic anhydride, mesaconicacid, ethylmaleic anhydride, dimethylmaleic anhydride, ethylmaleic acid,dimethylmaleic acid, hexylmaleic acid, and the like, including thecorresponding acid halides and lower aliphatic esters.

Hydrocarbyl-substituted succinic anhydrides are conventionally preparedby heating a mixture of maleic anhydride and an aliphatic olefin at atemperature of about 175° to about 275° C. The molecular weight of theolefin can vary depending upon the intended use of the substitutedsuccinic anhydrides. Typically, the substituted succinic anhydrides willhave a hydrocarbyl group of from 8-500 carbon atoms. However,substituted succinic anhydrides used to make lubricating oil dispersantswill typically have a hydrocarbyl group of about 40-500 carbon atoms.Dispersants having a hydrocarbyl group containing from about 8 to about150 carbon atoms are referred to herein as “relatively low molecularweight dispersants.” Whereas dispersants having a hydrocarbyl groupcontaining more than about 150 carbon atoms up to about 500 carbon atomsare referred to herein as “relatively high molecular weightdispersants.” With the very high molecular weight substituted succinicanhydrides, it is more accurate to refer to number average molecularweight (Mn) since the olefins used to make these substituted succinicanhydrides may include a mixture of different molecular weightcomponents resulting from the polymerization of low molecular weightolefin monomers such as ethylene, propylene and isobutylene.

The mole ratio of maleic anhydride to olefin can vary widely. It mayvary, for example, from 5:1 to 1:5, a more preferred range is 1:1 to3:1. With olefins such as polyisobutylene having a number averagemolecular weight of 500 to 7000, preferably 800 to 3000 or higher andthe ethylene-alpha-olefin copolymers, the maleic anhydride is preferablyused in stoichiometric excess, e.g. 1.1 to 3 moles maleic anhydride permole of olefin. The unreacted maleic anhydride can be vaporized from theresultant reaction mixture.

The hydrocarbyl-substituted succinic anhydrides include polyalkyl orpolyalkenyl succinic anhydrides prepared by the reaction of maleicanhydride with the desired polyolefin or chlorinated polyolefin, underreaction conditions well known in the art. For example, such succinicanhydrides may be prepared by the thermal reaction of a polyolefin andmaleic anhydride, as described in U.S. Pat. Nos. 3,361,673; 3,676,089;and 5,454,964. Alternatively, the substituted succinic anhydrides can beprepared by the reaction of chlorinated polyolefins with maleicanhydride, as described, for example, in U.S. Pat. No. 3,172,892. Afurther discussion of hydrocarbyl-substituted succinic anhydrides can befound, for example, in U.S. Pat. Nos. 4,234,435; 5,620,486 and5,393,309. Typically, these hydrocarbyl-substituents will contain from40 to 500 carbon atoms.

Polyalkenyl succinic anhydrides may be converted to polyalkyl succinicanhydrides by using conventional reducing conditions such as catalytichydrogenation. For catalytic hydrogenation, a preferred catalyst ispalladium on carbon. Likewise, polyalkenyl succinimides may be convertedto polyalkyl succinimides using similar reducing conditions.

The polyalkyl or polyalkenyl substituent on the succinic anhydridesemployed herein is generally derived from polyolefins which are polymersor copolymers of mono-olefins, particularly 1-mono-olefins, such asethylene, propylene and butylene. Preferably, the mono-olefin employedwill have 2 to about 24 carbon atoms, and more preferably, about 3 to 12carbon atoms. More preferred mono-olefins include propylene, butylene,particularly isobutylene, 1-octene and 1-decene. Polyolefins preparedfrom such mono-olefins include polypropylene, polybutene, polyisobutene,and the polyalphaolefins produced from 1-octene and 1-decene.

Dispersants may be prepared, for example, by reacting thehydrocarbyl-substituted succinic acids or anhydrides with an amine.Preferred amines are selected from polyamines and hydroxyamines.Examples of polyamines that may be used include, but are not limited to,aminoguanidine bicarbonate (AGBC), diethylene triamine (DETA),triethylene tetramine (TETA), tetraethylene pentamine (TEPA),pentaethylene hexamine (PEHA) and heavy polyamines. A heavy polyamine isa mixture of polyalkylenepolyamines comprising small amounts of lowerpolyamine oligomers such as TEPA and PEHA but primarily oligomers with 7or more nitrogen atoms, 2 or more primary amines per molecule, and moreextensive branching than conventional polyamine mixtures.

Polyamines that are also suitable in preparing the dispersants describedherein include N-arylphenylenediamines, such asN-phenylphenylenediamines, for example, N-phenyl-1,4-phenylenediamine,N-phenyl-1,3-phenylendiamine, and N-phenyl-1,2-phenylenediamine;aminothiazoles such as aminothiazole, aminobenzothiazole,aminobenzothiadiazole and aminoalkylthiazole; aminocarbazoles;aminoindoles; aminopyrroles; amino-indazolinones;aminomercaptotriazoles; aminoperimidines; aminoalkyl imidazoles, such as1-(2-aminoethyl)imidazole, 1-(3-aminopropyl)imidazole; and aminoalkylmorpholines, such as 4-(3-aminopropyl)morpholine. These polyamines aredescribed in more detail in U.S. Pat. Nos. 4,863,623; and 5,075,383.Such polyamines can provide additional benefits, such as anti-wear andantioxidancy, to the final products.

Additional polyamines useful in forming the hydrocarbyl-substitutedsuccinimides include polyamines having at least one primary or secondaryamino group and at least one tertiary amino group in the molecule astaught in U.S. Pat. Nos. 5,634,951 and 5,725,612. Examples of suitablepolyamines include N,N,N″,N″-tetraalkyldialkylenetriamines (two terminaltertiary amino groups and one central secondary amino group),N,N,N′,N′″-tetraalkyltrialkylenetetramines (one terminal tertiary aminogroup, two internal tertiary amino groups and one terminal primary aminogroup), N,N,N′,N″,N′″-pentaalkyltrialkylenetetramines (one terminaltertiary amino group, two internal tertiary amino groups and oneterminal secondary amino group),tris(dialkylaminoalkyl)aminoalkylmethanes (three terminal tertiary aminogroups and one terminal primary amino group), and like compounds,wherein the alkyl groups are the same or different and typically containno more than about 12 carbon atoms each, and which preferably containfrom I to 4 carbon atoms each. Most preferably these alkyl groups aremethyl and/or ethyl groups. Preferred polyamine reactants of this typeinclude dimethylaminopropylamine (DMAPA) and N-methyl piperazine.

Hydroxyamines suitable for herein include compounds, oligomers orpolymers containing at least one primary or secondary amine capable ofreacting with the hydrocarbyl-substituted succinic acid or anhydride.Examples of hydroxyamines suitable for use herein includeaminoethylethanolamine (AEEA), aminopropyldiethanolamine (APDEA),ethanolamine, diethanolamine (DEA), partially propoxylated hexamethylenediamine (for example HMDA-2PO or HMDA-3PO), 3-amino-1,2-propanediol,tris(hydroxymethyl)aminomethane, and 2-amino-1,3-propanediol.

The mol ratio of amine to hydrocarbyl-substituted succinic acid oranhydride preferably ranges from 1:1 to about 2.5:1. A particularlypreferred mol ratio of amine to hydrocarbyl-substituted succinic acid oranhydride ranges from about 1.5:1 to about 2.0:1.

The foregoing dispersant may also be a post-treated dispersant made, forexample, by treating the dispersant with maleic anhydride and boric acidas described, for example, in U.S. Pat. No. 5,789,353 to Scattergood, orby treating the dispersant with nonylphenol, formaldehyde and glycolicacid as described, for example, in U.S. Pat. No. 5,137,980 to DeGonia,et al.

The Mannich base dispersants are preferably a reaction product of analkyl phenol, typically having a long chain alkyl substituent on thering, with one or more aliphatic aldehydes containing from 1 to about 7carbon atoms (especially formaldehyde and derivatives thereof), andpolyamines (especially polyalkylene polyamines). Examples of Mannichcondensation products, and methods for their production are described inU.S. Pat. Nos. 2,459,112; 2,962,442; 2,984,550; 3,036,003; 3,166,516;3,236,770; 3,368,972; 3,413,347; 3,442,808; 3,448,047; 3,454,497;3,459,661; 3,493,520; 3,539,633; 3,558,743; 3,586,629; 3,591,598;3,600,372; 3,634,515; 3,649,229; 3,697,574; 3,703,536; 3,704,308;3,725,277; 3,725,480; 3,726,882; 3,736,357; 3,751,365; 3,756,953;3,793,202; 3,798,165; 3,798,247; 3,803,039; 3,872,019; 3,904,595;3,957,746; 3,980,569; 3,985,802; 4,006,089; 4,011,380; 4,025,451;4,058,468; 4,083,699; 4,090,854; 4,354,950; and 4,485,023.

The preferred hydrocarbon sources for preparation of the Mannichpolyamine dispersants are those derived from substantially saturatedpetroleum fractions and olefin polymers, preferably polymers ofmono-olefins having from 2 to about 6 carbon atoms. The hydrocarbonsource generally contains at least about 40 and preferably at leastabout 50 carbon atoms to provide substantial oil solubility to thedispersant. The olefin polymers having a GPC number average molecularweight between about 600 and 5,000 are preferred for reasons of easyreactivity and low cost. However, polymers of higher molecular weightcan also be used. Especially suitable hydrocarbon sources areisobutylene polymers and polymers made from a mixture of isobutene and araffinate I stream.

The preferred Mannich base dispersants are Mannich base ashlessdispersants formed by condensing about one molar proportion of longchain hydrocarbon-substituted phenol with from about 1 to 2.5 moles offormaldehyde and from about 0.5 to 2 moles of polyalkylene polyamine.

Polymeric polyamine dispersants suitable as the ashless dispersants arepolymers containing basic amine groups and oil solubilizing groups (forexample, pendant alkyl groups having at least about 8 carbon atoms).Such materials are illustrated by interpolymers formed from variousmonomers such as decyl methacrylate, vinyl decyl ether or relativelyhigh molecular weight olefins, with aminoalkyl acrylates and aminoalkylacrylam ides. Examples of polymeric polyamine dispersants are set forthin U.S. Pat. Nos. 3,329,658; 3,449,250; 3,493,520; 3,519,565; 3,666,730;3,687,849; and 3,702,300. The preferred polymeric polyamines arehydrocarbyl polyamines wherein the hydrocarbyl group is composed of thepolymerization product of isobutene and a raffinate I stream asdescribed above. PIB-amine and PIB-polyamines may also be used.

Another component of the dispersant compositions according to theembodiments described herein is a multi-functional viscosity indeximprover such as known in the art and are commercially available. Theseproducts and the processes for making them are taught in, for example,U.S. Pat. Nos. 4,732,942; 4,863,623; 5,075,383; 5,112,508; 5,238,588;and 6,107,257, each of which is incorporated herein by reference.

The multi-function viscosity index improver is preferably a nitrogencontaining viscosity index improver. Multi-functional viscosity indeximprovers include the reaction product of a nitrogen or an oxygen andnitrogen containing ethylenically unsaturated, aliphatic or aromaticmonomer grafted on to an olefin copolymer. Suitable nitrogen or oxygenand nitrogen containing ethylenically unsaturated monomers includeN-vinyl imidazole, 1-vinyl-2-pyrrolidinone, N-allyl imidazole, allylamines, 1-vinyl pyrrolidone, 2-vinyl pyridine, 4-vinyl pyridine,N-methyl-N-vinyl acetamide, diallyl formamide, N-methyl-N-allylformamide, N-ethyl-N-allyl formamide, N-cyclohexyl-N-allyl formamide,4-methyl-5-vinyl thiazole, N-allyl di-iso-octyl phenothiazine,2-methyl-1-vinylimidazole, 3-methyl-1-vinylpyrazole, N-vinyl purine,N-vinyl piperazines, N-vinyl succinimide, vinylpiperidines,vinylmorpholines, N-arylphenylenediamines, and mixtures thereof.

The multi-functional copolymers described above, as well as processesfor preparing them, are taught in U.S. Pat. Nos. 4,092,255; 4,170,561;4,146,489; 4,715,975; 4,769,043; 4,810,754; 5,294,354; 5,523,008;5,663,126; and 5,814,586; and 6,187,721, each of which is incorporatedherein by reference. Of the foregoing, a particularly preferred nitrogencontaining viscosity index improver is a reaction product of a maleicanhydride grafted ethylene-propylene copolymer and anN-arylphenylenediamine having a number average molecular weight rangingfrom about 5,000 to about 50,000. The amount of viscosity index improverin a lubricant composition according to an embodiment ranges from abouttwo to about twelve percent by weight based on the total weight of thelubricant composition.

Non-dispersant viscosity index improvers may be used in the alternativeor in combination with the foregoing nitrogen containing viscosity indeximprovers. Such non-dispersant viscosity index improvers include, butare not limited to, olefin copolymers, polyalkylmethacrylates, andstyrene-maleic esters. Of these, polyalkylmethacrylates are particularlypreferred. The viscosity index improver may be supplied in the form of asolution in an inert solvent, typically a mineral oil solvent, whichusually is a severely refined mineral oil.

Suitable materials for use a viscosity index improvers includestyrene-maleic esters such as LUBRIZOL® 3702, LUBRIZOL® 3706 andLUBRIZOL® 3715 available from The Lubrizol Corporation;polyalkylmethacrylates such as those available from ROHM GmbH(Darmstadt, Germany) under the trade designations: VISCOPLEX® 5543,VISCOPLEX® 5548, VISCOPLEX® 5549, VISCOPLEX® 5550, VISCOPLEX® 5551 andVISCOPLEX® 5151, from Rohm & Haas Company (Philadelphia, Pa.) under thetrade designations ACRYLOID® 1277, ACRYLOID® 1265 and ACRYLOID® 1269,and from Ethyl Corporation (Richmond, Va.) under the trade designationHiTEC® 5710 VII; and olefin copolymer viscosity index improvers such asHiTEC® 5747 VII, HiTEC® 5751 VII, HiTEC® 5770 VII and HiTEC® 5772 VIIavailable from Ethyl Corporation and SHELLVIS® 200 available from ShellChemical Company. Mixtures of the foregoing products can also be used aswell as dispersant and dispersant-antioxidant viscosity index improves.

As set forth herein, a dispersant according to the embodiments describedherein includes a relatively high or relatively low molecular weightdispersant having a hydrocarbyl group derived from a polymerizationproduct of a raffinate I stream and isobutene or a mixture of a firstrelatively high molecular weight dispersant and a second relatively lowmolecular weight dispersant, and optionally a nitrogen-containingviscosity index improver. The first and second dispersants may be eachselected from a hydrocarbyl substituted succinimide, Mannich basedispersant provided by condensing a hydrocarbyl substituted phenol withformaldehyde and a polyalkylene polyamine, and a hydrocarbyl substitutedamine. At least one of the first and second dispersants preferably has anumber average molecular weight ranging from about 1800 to about 2500,and at least one of the first and second dispersants preferably has anumber average molecular weight ranging from about 500 to about 1200 asdetermined by gel permeation chromatography. Most preferably, at leastone of the dispersants contains a hydrocarbyl group derived from apolymerization product of isobutene and a raffinate I stream.

Mixtures of the first and second dispersants may be made by combiningthe components in a conventional manner. It is preferred that the highermolecular weight dispersant be present in the mixture in an amountranging from about 30 to about 70% by weight, most preferably from about45 to about 65% by weight of the total weight of the mixed dispersants.Accordingly, the lower molecular weight dispersant is preferably presentin the mixture in an amount ranging from about 70 to about 30% byweight, most preferably from about 35 to about 45% by weight of thetotal weight of the mixed dispersants. The total amount of dispersant ina lubricant formulation preferably ranges from about I to about 10% byweight, more preferably from about 3 to about 6% by weight of the totallubricant formulation weight.

The following example is given for the purpose of exemplifying aspectsof the embodiments and is not intended to limit the embodiments in anyway. In the following example, a lubricant containing differentdispersant and dispersant mixtures was used and Sequence IIIG enginetests were performed to determine the deposit rating in terms ofweighted piston deposit (WPD). The lubricant used for all of the runswas a blend of Group II and Group III lubricating oils, namely 50 wt. %Ultra-S VHVI4 Group III from S-Oils, 20 wt. % Conoco lIONPure-Performance Group II and 30 wt. % Conoco 225N Pure-PerformanceGroup II. The dispersants used in the following example were as follows:

-   -   HiTEC® 644 dispersant is a 1000 MW_(N) PIBSA plus a polyamine.    -   HiTEC® 646 dispersant is a 1300 MW_(N) PIBSA plus a polyamine.    -   HiTEC® 1921 dispersant is a 2100 MW_(N) PIBSA plus a polyamine        post treated with nonylphenol, formaldehyde, and glycolic acid        and having a SA/PIB mol ratio of greater than about 1.1.

All of the foregoing dispersants are available from Ethyl Corporation ofRichmond, Virginia. “PIBSA” is defined as polyisobutylene succinic acidor anhydride. The “SA/PIB” ratio is the number of moles of succinic acidor anhydride relative to the number of mols of P13 in the PIBSA adduct.

EXAMPLE 1

HiTEC ® 1921 HiTEC ® 644 HiTEC ® 646 Sample No. (wt. %) (wt. %) (wt. %)WPD 1 4.5 — — 2.50 2 2.5 2.6 — 4.29 3 2.5 — 2.6 2.96 4 3.5 2.0 — 3.70

As shown by the foregoing example, mixtures of dispersants (Sample Nos.2, 3, and 4) had a better WPD rating than an oil composition containinga single relatively high molecular weight dispersant (Sample No. 1). Thebest results, according to the foregoing example, were obtained when arelatively low molecular weight dispersant was mixed with a relativelyhigh molecular weight dispersant (Sample Nos. 2 and 4).

It is expected that other dispersants available from Ethyl Corporationwill perform similarly in dispersant mixtures as described herein. Forexample, the following dispersants are also available from EthylCorporation:

-   -   HiTEC® 643 dispersant is a 1300 MW_(N) PIBSA plus a polyamine        wherein the dispersant was post treated with maleic anhydride        and boric acid.    -   HiTEC® 1919 dispersant is a 2100 MW_(N) PIBSA plus a polyamine        post treated with nonylphenol, formaldehyde, and glycolic acid    -   HiTEC® 1932 dispersant is a 2100 MW_(N) PIBSA plus a polyamine        having a SA/PIB ratio of greater than about 1.1.    -   HiTEC® 7049 dispersant is a 2100 MW_(N) PIB-phenol Mannich        reaction product.

Dispersant mixtures may be made as shown in the following table 2 whichare merely representative of mixtures that may be made and used asdescribed herein and are not intended to limit the embodiments describedherein in any way. TABLE 2 PIB-amine PIB-Phenol HiTEC ® HiTEC ® HiTEC ®HiTEC ® 1000 Mannich 1919 1921 1932 644 MW_(N) 1000 MW_(N) (wt. %) (wt.%) (wt. %) (wt. %) (wt. %) (wt. %) 3.8 — — 1.6 — — — 3.8 — — 1.6 — — —3.8 — — 1.6 3.8 — — — 1.6 — 3.8 — — — — 1.6 — 3.8 — 1.6 — — — 3.8 — — —1.6 — — 3.8 1.6 — — — — 3.8 — 1.6 — 1.6 — — 3.8 — — — 1.6 — — 3.8 — — —1.6 — — 3.8 1.6 — — — 3.8 — 1.6 — — — — 3.8 — 1.6 — 3.8 — — — 1.6 — — —3.8 — — 1.6 3.8 — — — — 1.6 — 3.8 —

Base oils suitable for use in formulating lubricating oil compositionsmay be selected from any of the synthetic or natural oils or mixturesthereof. The synthetic base oils include alkyl esters of dicarboxylicacids, polyglycols and alcohols, poly-alpha-olefins, includingpolybutenes, alkyl benzenes, organic esters of phosphoric acids, andpolysilicone oils. Natural base oils include mineral lubrication oilswhich may vary widely as to their crude source, e.g., as to whether theyare paraffinic, naphthenic, or mixed paraffinic-naphthenic. The base oiltypically has a viscosity of about 2.5 to about 15 cSt and preferablyabout 2.5 to about 11 cSt at 100° C.

The base oil used which may be used to make lubricant compositions asdescribed herein may be selected from any of the base oils in Groups I-Vas specified in the American Petroleum Institute (API) Base OilInterchangeability Guidelines. Such base oil groups are as follows: BaseOil Sulfur Saturates Viscosity Group¹ (wt. %) (wt. %) Index GroupI >0.03 and/or <90 80 to 120 Group II ≦0.03 And ≧90 80 to 120 Group II≦0.03 And ≧90 ≧120 Group IV all polyalphaolefins (PAOs) Group V allothers not included in Groups I-IV¹Groups I-III are mineral oil base stocks.

The base oil may be selected from a natural oil, synthetic oil ormixture of natural and synthetic oils. Natural oils include animal oilsand vegetable oils (e.g., castor oil, lard oil) as well as minerallubricating oils such as liquid petroleum oils and solvent treated oracid-treated mineral lubricating oils of the paraffinic, naphthenic ormixed paraffinic-naphthenic types. Oils derived from coal or shale arealso suitable. Synthetic lubricating oils include hydrocarbon oils suchas polymerized and interpolymerized olefins (e.g., polybutylenes,polypropylenes, propylene isobutylene copolymers, etc.);poly(1-hexenes), poly-(1-octenes), poly(1-decenes), etc. and mixturesthereof; alkylbenzenes (e.g., dodecylbenzenes, tetradecylbenzenes,di-nonylbenzenes, di-(2-ethylhexyl)benzenes, etc.); polyphenyls (e.g.,biphenyls, terphenyl, alkylated polyphenyls, etc.); alkylated diphenylethers and alkylated diphenyl sulfides and the derivatives, analogs andhomologs thereof and the like.

Alkylene oxide polymers and interpolymers and derivatives thereof wherethe terminal hydroxyl groups have been modified by esterification,etherification, etc., constitute another class of known syntheticlubricating oils that can be used. Such oils are exemplified by the oilsprepared through polymerization of ethylene oxide or propylene oxide,the alkyl and aryl ethers of these polyoxyalkylene polymers (e.g.,methyl-polyisopropylene glycol ether having an average molecular weightof about 1000, diphenyl ether of polyethylene glycol having a molecularweight of about 500-1000, diethyl ether of polypropylene glycol having amolecular weight of about 1000-1500, etc.) or mono- and polycarboxylicesters thereof, for example, the acetic acid esters, mixed C₃₋₈ fattyacid esters, or the C₁₃ Oxo acid diester of tetraethylene glycol.

Another class of synthetic lubricating oils that can be used comprisesthe esters of dicarboxylic acids (e.g., phthalic acid, succinic acid,alkyl succinic acids, alkenyl succinic acids, maleic acid, azelaic acid,suberic acid, sebacic acid, fumaric acid, adipic acid, linoleic aciddimer, malonic acid, alkyl malonic acids, alkenyl malonic acids, etc.)with a variety of alcohols (e.g., butyl alcohol, hexyl alcohol, dodecylalcohol, 2-ethylhexyl alcohol, ethylene glycol, diethylene glycolmonoether, propylene glycol, etc.) Specific examples of these estersinclude dibutyl adipate, di(2-ethylhexyl)sebacate, di-n-hexyl fumarate,dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctylphthalate, didecyl phthalate, dieicosyl sebacate, the 2-ethylhexyldiester of linoleic acid dimer, the complex ester formed by reacting onemole of sebacic acid with two moles of tetraethylene glycol and twomoles of 2-ethylhexanoic acid and the like.

Esters useful as synthetic oils also include those made from C₅ to C₁₂monocarboxylic acids and polyols and polyol ethers such as neopentylglycol, trimethylol propane, pentaerythritol, dipentaerythritol,tripentaerythritol, etc.

As set forth above, the base oil may be a poly-alpha-olefin (PAO).Typically, the poly-alpha-olefins are derived from monomers having fromabout 4 to about 30, or from about 4 to about 20, or from about 6 toabout 16 carbon atoms. Examples of useful PAOs include those derivedfrom octene, decene, mixtures thereof, and the like. PAOs may have aviscosity from about 2 to about 15, or from about 3 to about 12, or fromabout 4 to about 8 cSt at 100° C. Examples of PAOs include 4-cSt at 100°C. poly-alpha-olefins, 6 cSt at 100° C. poly-alpha-olefins, and mixturesthereof. Mixtures of mineral oil with the foregoing poly-alpha-olefinsmay be used.

The base oil may be an oil derived from Fischer-Tropsch synthesizedhydrocarbons. Fischer-Tropsch synthesized hydrocarbons are made fromsynthesis gas containing H₂ and CO using a Fischer-Tropsch catalyst.Such hydrocarbons typically require further processing in order to beuseful as the base oil. For example, the hydrocarbons may behydroisomerized using the process disclosed in U.S. Pat. Nos. 6,103,099or 6,180,575; hydrocracked and hydroisomerized using the processdisclosed in U.S. Pat. Nos. 4,943,672 or 6,096,940; dewaxed using theprocess disclosed in U.S. Pat. No. 5,882,505; or hydroisomerized anddewaxed using the process disclosed in U.S. Pat. Nos. 6,013,171,6,080,301 or 6,165,949.

Unrefined, refined and rerefined oils, either natural or synthetic (aswell as mixtures of two or more of any of these) of the type disclosedhereinabove can be used in the lubricant base oils. Unrefined oils arethose obtained directly from a natural or synthetic source withoutfurther purification treatment. For example, a shale oil obtaineddirectly from retorting operations, a petroleum oil obtained directlyfrom primary distillation or ester oil obtained directly from anesterification process and used without further treatment would be anunrefined oil. Refined oils are similar to the unrefined oils exceptthey have been further treated in one or more purification steps toimprove one or more properties. Many such purification techniques areknown to those skilled in the art such as solvent extraction, secondarydistillation, acid or base extraction, filtration, percolation, etc.Rerefined oils are obtained by processes similar to those used to obtainrefined oils applied to refined oils which have been already used inservice. Such rerefined oils are also known as reclaimed or reprocessedoils and often are additionally processed by techniques directed toremoval of spent additives, contaminants, and oil breakdown products.

Additives used in formulating the compositions described herein can beblended into the base oil individually or in various sub-combinations.However, it is preferable to blend all of the components concurrentlyusing an additive concentrate (i.e., additives plus a diluent, such as ahydrocarbon solvent). The use of an additive concentrate takes advantageof the mutual compatibility afforded by the combination of ingredientswhen in the form of an additive concentrate. Also, the use of aconcentrate reduces blending time and lessens the possibility ofblending errors.

One embodiment is directed to a method of reducing wear in an internalcombustion engine, wherein said method comprises using as the crankcaselubricating oil for said internal combustion engine a lubricating oilcontaining the dispersant or mixture of dispersants as described herein,wherein the dispersant is present in an amount sufficient to reduce thewear in an internal combustion engine operated using said crankcaselubricating oil, as compared to the wear in said engine operated in thesame manner and using the same crankcase lubricating oil except that theoil is devoid of the dispersant or dispersant mixture. Accordingly, forreducing wear, the dispersant or dispersant mixture is typically presentin the lubricating oil in an amount of from 0.1 to 3 weight percentbased on the total weight of the oil. Representative of the types ofwear that may be reduced using the compositions described herein includecam wear and lifter wear. In other embodiments, the lubricantcompositions described herein may be used or formulated as gear oil,hydraulic oils, automatic transmission fluids, and the like.

At numerous places throughout this specification, reference has beenmade to a number of U.S. Patents. All such cited documents are expresslyincorporated in full into this disclosure as if fully set forth herein.

The foregoing embodiments are susceptible to considerable variation inits practice. Accordingly, the embodiments are not intended to belimited to the specific exemplifications set forth hereinabove. Rather,the foregoing embodiments are within the spirit and scope of theappended claims, including the equivalents thereof available as a matterof law.

The patentees do not intend to dedicate any disclosed embodiments to thepublic, and to the extent any disclosed modifications or alterations maynot literally fall within the scope of the claims, they are consideredto be part hereof under the doctrine of equivalents.

1. A dispersant for use as a lubricant additive, comprising at least onemember selected from the group consisting of hydrocarbyl-substitutedsuccinimides, hydrocarbyl-substituted amines, and Mannich base adductsderived from hydrocarbyl-substituted phenols condensed with aldehydesand amines, wherein the hydrocarbyl substituent is comprised of apolymerization product of a raffinate I stream and isobutylene having anumber average molecular weight ranging from about 500 to about 3000 asdetermined by gel permeation chromatography and more than about 70 molpercent of the polymerization product having a terminal vinylidenegroup.
 2. The dispersant of claim 1, wherein the polymerization productis derived from a reaction mixture including from about 35 to about 45weight percent isobutylene and from about 55 to about 65 weight percentraffinate I stream.
 3. The dispersant of claim 1 comprising ahydrocarbyl-substituted succinimide derived from the polymerizationproduct and succinic acid having a ratio of polymerization product tosuccinic acid ranging from about 1.0:1.0 to about 1.0:1.6.
 4. Thedispersant of claim 1 comprising a Mannich adduct derived fromhydrocarbyl-substituted phenols, formaldehydes and polyethylenepolyamines.
 5. The dispersant of claim 1 further comprising a nitrogencontaining viscosity index improver selected from the group consistingof N-vinyl imidazole, 1-vinyl-2-pyrrolidinone, N-allyl imidazole, allylamines, 1-vinyl pyrrolidone, 2-vinyl pyridine, 4-vinyl pyridine,N-methyl-N-vinyl acetamide, diallyl formamide, N-methyl-N-allylformamide, N-ethyl-N-allyl formamide, N-cyclohexyl-N-allyl formamide,4-methyl-5-vinyl thiazole, N-allyl di-iso-octyl phenothiazine,2-methyl-1-vinylimidazole, 3-methyl-1-vinylpyrazole, N-vinyl purine,N-vinyl piperazines, N-vinyl succinimide, vinylpiperidines,vinylmorpholines, N-arylphenylenediamines, and mixtures thereof.
 6. Thedispersant of claim 5 wherein the nitrogen containing viscosity indeximprover comprises a reaction product of a maleic anhydride graftedethylene-propylene copolymer and an N-arylphenylenediamine, wherein thereaction product has a number average molecular weight ranging fromabout 5,000 to about 50,000.
 7. The dispersant of claim 5 furthercomprising a non-dispersant viscosity index improver selected from thegroup consisting of olefin copolymers, polyalkylmethacrylates, andstyrene-maleic esters.
 8. The dispersant of claim 5 wherein thepolymerization product has a number average molecular weight rangingfrom about 500 to about 1200 as determined by gel permeationchromatography.
 9. The dispersant of claim 1 further comprising anon-dispersant viscosity index improver selected from the groupconsisting of olefin copolymers, polyalkylmethacrylates, andstyrene-maleic esters.
 10. The dispersant of claim 9 wherein thepolymerization product has a number average molecular weight rangingfrom about 500 to about 1200 as determined by gel permeationchromatography.
 11. A lubricant composition comprising an oil oflubricating viscosity and from about 0.1 to 10 wt. %, based on the totalweight of the lubricant composition, of the dispersant of claim
 5. 12. Avehicle having moving parts and containing a lubricant for lubricatingthe moving parts, the lubricant comprising an oil of lubricatingviscosity and from about 0.1 to 10 wt. %, based on the total weight ofthe lubricant composition, of the dispersant of claim
 1. 13. A lubricantadditive comprising a first dispersant and a second dispersant selectedfrom the group consisting of hydrocarbyl-substituted succinimides,hydrocarbyl-substituted amines, and Mannich base adducts derived fromhydrocarbyl-substituted phenols condensed with aldehydes and amines,wherein the first dispersant is the dispersant of claim
 1. 14. Thelubricant additive of claim 13 further comprising a nitrogen containingviscosity index improver selected from the group consisting of N-vinylimidazole, 1-vinyl-2-pyrrolidinone, N-allyl imidazole, allyl amines,1-vinyl pyrrolidone, 2-vinyl pyridine, 4-vinyl pyridine,N-methyl-N-vinyl acetamide, diallyl formamide, N-methyl-N-allylformamide, N-ethyl-N-allyl formamide, N-cyclohexyl-N-allyl formamide,4-methyl-5-vinyl thiazole, N-allyl di-iso-octyl phenothiazine,2-methyl-1-vinylimidazole, 3-methyl-1-vinylpyrazole, N-vinyl purine,N-vinyl piperazines, N-vinyl succinimide, vinylpiperidines,vinylmorpholines, N-arylphenylenediamines, and mixtures thereof.
 15. Thelubricant additive of claim 14 wherein the nitrogen containing viscosityindex improver comprises a reaction product of a maleic anhydridegrafted ethylene-propylene copolymer and an N-arylphenylenediamine,wherein the reaction product has a number average molecular weightranging from about 5,000 to about 50,000.
 16. The lubricant additive ofclaim 14 further comprising a non-dispersant viscosity index improverselected from the group consisting of olefin copolymers,polyalkylmethacrylates, and styrene-maleic esters.
 17. The lubricantadditive of claim 13 further comprising a non-dispersant viscosity indeximprover selected from the group consisting of olefin copolymers,polyalkylmethacrylates, and styrene-maleic esters.
 18. A lubricantcomposition comprising an oil of lubricating viscosity and from about0.1 to 10 wt. %, based on the total weight of the lubricant composition,of the lubricant additive of claim
 13. 19. A lubricant additivecomprising: a first dispersant including at least one member selectedfrom the group consisting of hydrocarbyl-substituted succinimides,hydrocarbyl-substituted amines, and Mannich base adducts derived fromhydrocarbyl-substituted phenols condensed with aldehydes and amines; anda second dispersant including a member selected from the grouphydrocarbyl-substituted succinimides, hydrocarbyl-substituted amines,and Mannich base adducts derived from hydrocarbyl-substituted phenolscondensed with aldehydes and amines, wherein the hydrocarbyl substituentof the first dispersant has a number average molecular weight rangingfrom about 1500 to about 2500 as determined by gel permeationchromatography and wherein the second dispersant has a number averagemolecular weight ranging from about 500 to about 1200 as determined bygel permeation chromatography.
 20. The lubricant additive of claim 19further comprising a nitrogen containing viscosity index improverselected from the group consisting of N-vinyl imidazole,1-vinyl-2-pyrrolidinone, N-allyl imidazole, allyl amines, 1-vinylpyrrolidone, 2-vinyl pyridine, 4-vinyl pyridine, N-methyl-N-vinylacetamide, diallyl formamide, N-methyl-N-allyl formamide,N-ethyl-N-allyl formamide, N-cyclohexyl-N-allyl formamide,4-methyl-5-vinyl thiazole, N-allyl di-iso-octyl phenothiazine,2-methyl-1-vinylimidazole, 3-methyl-1-vinylpyrazole, N-vinyl purine,N-vinyl piperazines, N-vinyl succinimide, vinylpiperidines,vinylmorpholines, N-arylphenylenediamines, and mixtures thereof.
 21. Thelubricant additive of claim 20 wherein the nitrogen containing viscosityindex improver comprises a reaction product of a maleic anhydridegrafted ethylene-propylene copolymer and an N-arylphenylenediamine,wherein the reaction product has a number average molecular weightranging from about 5,000 to about 50,000.
 22. The lubricant additive ofclaim 20 further comprising a non-dispersant viscosity index improverselected from the group consisting of olefin copolymers,polyalkylmethacrylates, and styrene-maleic esters.
 23. The lubricantadditive of claim 19 further comprising a non-dispersant viscosity indeximprover selected from the group consisting of olefin copolymers,polyalkylmethacrylates, and styrene-maleic esters.
 24. The lubricantadditive of claim 19, wherein the hydrocarbyl-substituent of at leastone of the first and second dispersants comprises a polymerizationproduct derived from a reaction mixture including from about 35 to about45 weight percent isobutylene and from about 55 to about 65 weightpercent raffinate I stream.
 25. The lubricant additive of claim 19,wherein at least one of the first and second dispersants comprises ahydrocarbyl-substituted succinic acid derivative.
 26. The lubricantadditive of claim 25, wherein the hydrocarbyl-substituent comprises apolymerization product derived from a reaction mixture including fromabout 35 to about 45 weight percent isobutylene and from about 55 toabout 65 weight percent raffinate I stream.
 27. The lubricant additiveof claim 25, wherein the first dispersant is a post treated dispersant.28. The lubricant additive of claim 19, wherein at least one of thefirst and second dispersants comprises a Mannich base adduct derivedfrom a hydrocarbyl-substituted phenol condensed with an aldehyde and anamine.
 29. The lubricant additive of claim 28, wherein thehydrocarbyl-substituent comprises a polymerization product derived froma reaction mixture including from about 35 to about 45 weight percentisobutylene and from about 55 to about 65 weight percent raffinate Istream.
 30. A lubricant composition comprising an oil of lubricatingviscosity and from about 0.1 to 10 wt. %, based on the total weight ofthe lubricant composition, of the lubricant additive of claim
 19. 31.The lubricant additive of claim 19 containing from about 30 to about 70percent by weight of the first dispersant and from about 70 to about 30percent by weight of the second dispersant.
 32. A method of lubricatingmoving parts of a vehicle, the method comprising using as a lubricatingoil for one or more moving parts of the vehicle a lubricant compositioncontaining a lubricant and a lubricant additive, the lubricant additiveincluding: a first dispersant including at least one member selectedfrom the group consisting of hydrocarbyl-substituted succinimides,hydrocarbyl-substituted amines, and Mannich base adducts derived fromhydrocarbyl-substituted phenols condensed with aldehydes and amines; anda second dispersant including a member selected from the grouphydrocarbyl-substituted succinimides, hydrocarbyl-substituted amines,and Mannich base adducts derived from hydrocarbyl-substituted phenolscondensed with aldehydes and amines, wherein the hydrocarbyl substituentof the first dispersant has a number average molecular weight rangingfrom about 1500 to about 2500 as determined by gel permeationchromatography and wherein the second dispersant has a number averagemolecular weight ranging from about 500 to about 1200 as determined bygel permeation chromatography, and wherein the lubricant additive ispresent in the lubricant composition in an amount sufficient tolubricate the one or more moving parts of the vehicle.
 33. The method ofclaim 32 wherein the vehicle includes an internal combustion enginehaving a crankcase and wherein the lubricant composition comprises acrankcase oil present in the crankcase of the vehicle.
 34. The method ofclaim 32 wherein the lubricant composition comprises an drive trainlubricant present in an automotive drive train of the vehicle.
 35. Themethod of claim 32 wherein the lubricant additive includes a nitrogencontaining viscosity index improver selected from the group consistingof N-vinyl imidazole, 1-vinyl-2-pyrrolidinone, N-allyl imidazole, allylamines, 1-vinyl pyrrolidone, 2-vinyl pyridine, 4-vinyl pyridine,N-methyl-N-vinyl acetamide, diallyl formamide, N-methyl-N-allylformamide, N-ethyl-N-allyl formamide, N-cyclohexyl-N-allyl formamide,4-methyl-5-vinyl thiazole, N-allyl di-iso-octyl phenothiazine,2-methyl-1-vinylimidazole, 3-methyl-1-vinylpyrazole, N-vinyl purine,N-vinyl piperazines, N-vinyl succinimide, vinylpiperidines,vinylmorpholines, N-arylphenylenediamines, and mixtures thereof.
 36. Themethod of claim 35 wherein the nitrogen containing viscosity indeximprover comprises a reaction product of a maleic anhydride graftedethylene-propylene copolymer and an N-arylphenylenediamine, wherein thereaction product has a number average molecular weight ranging fromabout 5,000 to about 50,000.
 37. The method of claim 35 furthercomprising a non-dispersant viscosity index improver selected from thegroup consisting of olefin copolymers, polyalkylmethacrylates, andstyrene-maleic esters.
 38. The method of claim 32 further comprising anon-dispersant viscosity index improver selected from the groupconsisting of olefin copolymers, polyalkylmethacrylates, andstyrene-maleic esters.
 39. The method of claim 32, wherein thehydrocarbyl-substituent of at least one of the first and seconddispersants comprises a polymerization product derived from a reactionmixture including from about 35 to about 45 weight percent isobutyleneand from about 55 to about 65 weight percent raffinate I stream.
 40. Themethod of claim 32, wherein at least one of the first and seconddispersants comprises a hydrocarbyl-substituted succinic acidderivative.
 41. The method of claim 40, wherein thehydrocarbyl-substituent comprises a polymerization product derived froma reaction mixture including from about 35 to about 45 weight percentisobutylene and from about 55 to about 65 weight percent raffinate Istream.
 42. The method of claim 40, wherein the first dispersant is apost treated dispersant.
 43. The method of claim 32, wherein at leastone of the first and second dispersants comprises a Mannich base adductderived from a hydrocarbyl-substituted phenol condensed with an aldehydeand an amine.
 44. The method of claim 43, wherein thehydrocarbyl-substituent comprises a polymerization product derived froma reaction mixture including from about 35 to about 45 weight percentisobutylene and from about 55 to about 65 weight percent raffinate Istream.
 45. A method for lubricating moving parts comprising contactingthe moving parts with a lubricant composition containing a lubricantadditive, the lubricant additive comprising: a first dispersantincluding at least one member selected from the group consisting ofhydrocarbyl-substituted succinimides, hydrocarbyl-substituted amines,and Mannich base adducts derived from hydrocarbyl-substituted phenolscondensed with aldehydes and amines; and a second dispersant including amember selected from the group hydrocarbyl-substituted succinimides,hydrocarbyl-substituted amines, and Mannich base adducts derived fromhydrocarbyl-substituted phenols condensed with aldehydes and amines,wherein the hydrocarbyl substituent of the first dispersant has a numberaverage molecular weight ranging from about 1500 to about 2500 asdetermined by gel permeation chromatography and wherein the seconddispersant has a number average molecular weight ranging from about 500to about 1200 as determined by gel permeation chromatography, andwherein the lubricant additive is present in the lubricant compositionin an amount sufficient to enhance the dispersability of particles inthe lubricant composition.
 46. The method of claim 45 wherein thelubricant composition includes a nitrogen containing viscosity indeximprover selected from the group consisting of N-vinyl imidazole,1-vinyl-2-pyrrolidinone, N-allyl imidazole, allyl amines, 1-vinylpyrrolidone, 2-vinyl pyridine, 4-vinyl pyridine, N-methyl-N-vinylacetamide, diallyl formamide, N-methyl-N-allyl formamide,N-ethyl-N-allyl formamide, N-cyclohexyl-N-allyl formamide,4-methyl-5-vinyl thiazole, N-allyl di-iso-octyl phenothiazine,2-methyl-1-vinylimidazole, 3-methyl-1-vinylpyrazole, N-vinyl purine,N-vinyl piperazines, N-vinyl succinimide, vinylpiperidines,vinylmorpholines, N-arylphenylenediamines, and mixtures thereof.
 47. Themethod of claim 46 wherein the nitrogen containing viscosity indeximprover comprises a reaction product of a maleic anhydride graftedethylene-propylene copolymer and an N-arylphenylenediamine, wherein thereaction product has a number average molecular weight ranging fromabout 5,000 to about 50,000.
 48. The method of claim 55, wherein thehydrocarbyl-substituent of at least one of the first and seconddispersants comprises a polymerization product derived from a reactionmixture including from about 35 to about 45 weight percent isobutyleneand from about 55 to about 65 weight percent raffinate I stream.
 49. Themethod of claim 45, wherein at least one of the first and seconddispersants comprises a hydrocarbyl-substituted succinic acidderivative.
 50. The method of claim 49, wherein thehydrocarbyl-substituent comprises a polymerization product derived froma reaction mixture including from about 35 to about 45 weight percentisobutylene and from about 55 to about 65 weight percent raffinate Istream.
 51. The method of claim 49, wherein the first dispersant is apost treated dispersant.
 52. The method of claim 45, wherein at leastone of the first and second dispersants comprises a Mannich base adductderived from a hydrocarbyl-substituted phenol condensed with an aldehydeand an amine.
 53. The method of claim 52, wherein thehydrocarbyl-substituent comprises a polymerization product derived froma reaction mixture including from about 35 to about 45 weight percentisobutylene and from about 55 to about 65 weight percent raffinate Istream.
 54. A method for lubricating moving parts of a vehicle, themethod comprising using as a lubricating oil for one or more movingparts of the vehicle a lubricant composition containing a lubricant anda dispersant additive in an effective amount, the dispersant comprisingat least one member selected from the group consisting ofhydrocarbyl-substituted succinimides, hydrocarbyl-substituted amines,and Mannich base adducts derived from hydrocarbyl-substituted phenolscondensed with aldehydes and amines, wherein the hydrocarbyl substituentis comprised of a polymerization product of a raffinate I stream andisobutylene having a number average molecular weight ranging from about500 to about 3000 as determined by gel permeation chromatography andmore than about 70 mol percent of the polymerization product having aterminal vinylidene group.
 55. The method of claim 54, wherein thepolymerization product is derived from a reaction mixture including fromabout 35 to about 45 weight percent isobutylene and from about 55 toabout 65 weight percent raffinate I stream.
 56. The method of claim 54wherein the dispersant comprises a hydrocarbyl-substituted succinimidederived from the polymerization product and succinic acid having a ratioof polymerization product to succinic acid ranging from about 1.0:1.0 toabout 1.0:1.6.
 57. The method of claim 54 wherein the dispersantcomprises a Mannich adduct derived from hydrocarbyl-substituted phenols,formaldehydes and polyethylene polyamines.
 58. The method of claim 54wherein the dispersant includes a nitrogen containing viscosity indeximprover selected from the group consisting of N-vinyl imidazole,1-vinyl-2-pyrrolidinone, N-allyl imidazole, allyl amines, 1-vinylpyrrolidone, 2-vinyl pyridine, 4-vinyl pyridine, N-methyl-N-vinylacetamide, diallyl formamide, N-methyl-N-allyl formamide,N-ethyl-N-allyl formamide, N-cyclohexyl-N-allyl formamide,4-methyl-5-vinyl thiazole, N-allyl di-iso-octyl phenothiazine,2-methyl-1-vinylimidazole, 3-methyl-1-vinylpyrazole, N-vinyl purine,N-vinyl piperazines, N-vinyl succinimide, vinylpiperidines,vinylmorpholines, N-arylphenylenediamines, and mixtures thereof.